Protective means for contact-terminals



C. A. BODDIE.

PROTECTIVE MEANS FOR CONTACT TERMINALS.

APPLICATION FILED NOV. 9, 1918.

Patented Nov. 16, 1920.

34 I \f 12 /3 MN:

INVENTOR C/arence A. Bodd/e.

WITNESSES;

ATTORNEY UNITED STATES PATENT ore-Ice.

CLARENCE A. BODDIE, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- $YLVANIA.I

PROTECTIVE MEANS FOR QONTACT-TERMINALS.

Specification of Letters Patent.

Patented Nov. 16, 1926.

Application filed November 9, 1918. Serial No. 261,925.

T 0 aZZ whom it may concern:

a citizen ofthe United States, and a resident of Pittsburgh, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in Protective Means for Contact-Terminals, of whichthe following is a specification.

My invention relates to protective means for contact terminals andparticularly to protective means for the main-contact members ofvoltage-regulator systems.

One object of my invention is to provide a pair of contact members, witha reactor connected in circuit therewith, that shall insure the contactmembers against injury from the inductive discharge of any inductancedevice which may be connected in circuit with them. I

In many electrical systems, and particularly in voltage-regulatorsystems, are con tact members, such, for example, as the maincontactmembers of a regulator, that are adjusted for very delicate operation,and any freezing or sticking of the contact members will, in many cases,destroy the opera tiveness of the system. Thus, in Voltageregulatorsystems of the vibratory-contact type, the main-contact members, whichare governed by a main-control electromagnet in accordance with thevoltage obtaining on a supply circuit, serve to intermittently connectan auxiliary electromagnet across an auxiliary supply circuitand,consequently, the main-contact .members are subjected to aninductive discharge from the winding of the auxiliary electromagnet.Inasmuch as the main-control magnet and the main-contact members, whichare governed thereby, are very delicately adjusted, it requires butlittle freezing or sticking of the main-contact members, by reason ofinductive discharges, to destroy the operativeness of the regulator.Accordingly, in case currents of relatively high value are to becontrolled by the main-contact members, the contact members must beprovided with protective means to insure them against sticking orfreezing, by reason of the large inductive discharges.

It is proposed to connect a resistor inbut such a protective means isonly of service for dissipating inductive discharges between very narrowlimits. In case a condenser and a resistor are connected in parallel tothe winding of the auxiliary magnet, inductive discharges of relativelylarge value may be dissipated without injury to the main-contact membersbut, upon closing of the contact members, the charging current for thecondenser will, in many cases, cause a freezing together of the contactmembers. Moreover, a condenser connected directly across the contactmembers is unsatisfactory by reason of the discharge from the condenserhaving as detrimental an effect upon the contact members as theinductive discharge from the winding of the auxiliary electromagnet.Upon connecting a resistor and a condenser in series across the maincontact members, the operation of the contact members is slightlyimproved. However, if the resistor is small, a freezing of the contactmembers is effected by reason of the discharge current from thecondenser and, if

the resistor is large, the effectiveness of the,

value was connected in series with the main-.

contact members and a condenser and a resistor were connected inparallel to'the winding of the auxiliary electromagnet, verysatisfactory operation of the contact members could be obtained for awide range of current values. However, inasmuch as a certain amount ofenergy is stored in a resistor when current is passing through it, somemeans should be provided for effecting a dischar e of the energy storedin the resistors. ccordingly, in accordance with the preferredmodification of my invention, the main contact members are connected inseries with the winding of the auxiliary electromagnet across a portionof a resistor, which is connected across the auxiliary supply circuit,and a resistor and a condenser are connected in parallel to the windingof the auxiliary electromagnet. Moreover, a protective resistor of arelatively high value is connected directly across the main-contactmembers.

In the accompanying drawing, Figure 1 is a diagrammatic view of aregulator system embodying my invention, and Figs. 2 to 5,

inclusive. illustrate various arrangements of reactors for protectingthe main-contact members of a regulator.

Referring to Fig. 1 of the drawing, a generator 1', comprising anarmature 2 and a field winding 3, is connected across a supply circuit,embodying conductors 4 and 5.

The voltage of the generator 1 is controlled by a regulator 6, whichembodies a main-control electromagnet 7 and an auxiliary electromagnet8. The main-control electromagnet 7 embodies a winding 9, which 'isconnected through a resistor 10 across the supply conductors 4 and 5,and a core armature 11, which is pivotally connected to a contact arm12.

The contact arm 12 is pivotally mounted at 13 and is provided with amain-contact member 14, which cooperates with a stationary main-contactmember 15. A spring 16 is connected to the contact arm 12 forcounterbalancing the weight of the core armature 11.

The auxiliary electromagnet 8 embodiesa winding 17 that is connected toan auxiliary supply circuit, comprising conductors 18 and 19, by.meansof the main-contact members 14 and 15. The auxiliary magnet alsoprovided with a core armature that 1s pivotally connected to a contactarm 20.

the release of the auxiliarymagnet 8, for

short-circuiting a resistor 24, which is included in the field circuitof the generator 1. The action of the electromagnet 8- upon the contactarm 20 is opposed by a spring 25.

My invention chiefly involves various arrangements of reactors that areprovided in the circuit of the winding 17 for protectin the main-contactmembers 14 and 15.

riefly, the operation of the regulator system illustrated in Fig.1 is asfollows: In case the voltage on the supply conductors 4 and 5 is abovenormal value, then the maincontrol electromagnet 7 is operated in amanner to close the contact members 14 and I ply conductors is reducedbelow normal,

value, the main-control electromagnet 7 is released to permit theseparation of the main-contact members 14 and 15. Upon separation of themain-contact members 14 and 15, the circuit of the auxiliary 6lGCtI'Oweaver magnet 8 is opened and, consequently, the contact arm 20 isoperated by the spring 25 to close the contact members 22 and 23. Uponengagement of the contact members 22 and 23, the resistor 24 isshort-circuited it .magnetic energy, it will cause sparking at themain-contact members.

In Fig. 2 of the drawing, a systemof reactances is illustrated whereinthe winding 17 ot'the auxiliary electromagnet 8 is shunted by a resistor30 to protect the contact members 14 and'15 against inductive dischargesfrom the winding 17. Such a means for protecting the main-contactmembers is practical only when the stored magnetic energy of the systemis small.

In Fi 3, is illustrated a system of reactors w erein the winding 17 ofthe auxil- Iiary electromagnet '8 is not only shunted by a resistor 30,but also by a condenser 31. Such an arrangement of reactances is verysatisfactory for dissipating the inductive discharges from the winding17 but, upon closing of the contact members 14 and 15, the chargingcurrent for the condenser 31 is ver liable to eiiect a freezing or asticking 0 the contact members 14 and 15. The arrangement is, therefore,of no use where delicate control contacts areinvolved.

Referring to Fig. 4 of the drawing, a sys tem of reactors is disclosedfor protecting the main contact members that is very satisfactory over awide range of current values.

In the system illustrated in Fig. 4, a con- 11 denser 31 and a resistor30 are connected in parallel to the winding 17 and a resistor'32 isprovided in series with the contact members 14 and 15. The condenser 31and the resistor 30 serve to prevent injury to the 11:

contact members 14 and 15 by the inductive discharges from the winding17, and the resistor 32 serves to prevent an 'excessive charging currentfor the condenser 31 from""" passing through the main-contact members 14and 15.

It is well known that more or .less energy may be stored in resistorsand, in order to take care of the energy which may be stored in theresistors shown in the system disclosed in Fig. '4, an improved systemof reactors, such as is disclosed in Fig. 5, is provided. In the systemillustrated in Fig. 5, a resistor 33, which is divided into .portions 33and 33 is connected directly across the supply conductors 18 and 19, andthe winding 17, which is shunted by the condenser 31 and the resistor80, is connected in'shunt to the resistor section 33 by means of themain contact members 14; and 15. Moreover, a protective resistor 34;, ofa relatively high value, is connected across the contact members 14 and15. The resistor section 33 serves as aby-pass for freeing the contactmembers from any discharge from the resistor 33 The system of reactancesshown in Fig. 5 has also been illustrated in Fig. 1- andany furtherdescription of Fig. 1, in connection with the various reactances, isdeemed unnecessary.

Modifications in the system and arrangement and location of parts may bemade within the scope of my invention, and such modifications areintended to be covered by the appended claims.

I claim as my invention:

1. In an electrical system, a supply circuit, a pair of contact membersfor bridg-' ing the supply circuit, an inductance device in series withsaid contact members, and means comprising a resistor and a condenserconnected in parallel to said inductance device for protecting thecontact members against inductive discharges.

2. In an electrical system, a supply circuit, a pair of contact membersfor bridging said supply circuit, an inductance device in series withsaid contact members, means comprising a resistor and a condenserconnected in parallel to said inductance device for protecting thecontact members against inductive discharges, and a resistor in serieswith the contact members for limiting the current flow through thecondenser upon closure of the contact members.

3. In an electrical system, a supply circuit, a two-part resistorconnected acrossthe supply circuit, a pair of contact members forestablishing a circuit in shunt to one portion of said resistor, aninductance device in said shunt circuit, and a condenser and a resistorconnected in parallel to said inductance device for protecting thecontact members against inductive discharges.

4. In an electrical system, a supply circuit, a resistor connectedacross the supply circuit, a pair of contact members for establishing acircuit in shunt to a portion of said resistor, an inductance device insaid shunt circuit, a protective resistor of relatively high valueconnected across'the contact members, and a condenser and a resistorconnected in parallel to said inductance device for protecting thecontact members against inductive discharges.

5. In an electric system, a supply circuit, a resistor and a pair ofcontact members connected in series across the supply circuit, aninductance device in series with said contact members, a protectiveresistor of relatively high value connected across the contact members,and a condenser and a resistor connected in parallel to the inductancedevice for protecting the contact members against inductive discharges.

6. In a regulator system, a main-control electromagnet operated inaccordance with the voltage obtaining on a supply circuit, an auxiliaryelectromagnet, a pair of maincontact members for connecting theauxiliary magnet across an auxiliary supply circuit, and a resistor anda condenser connected in parallel to said auxiliary electromagnet forprotecting the main-contact members against inductive discharges.

7 In a regulator system, a main-control electromagnet, an auxiliaryelectromagnet, a supply circuit, a pair of contact members governed bythe main-control electromagnet for connecting the auxiliary magnetacross the supply circuit, a protecting resistor of relatively highvalue connected across the contact members, and a condenser and aresistor connected in parallel to the auxiliary magnet for protectingthe contact members against inductive discharges.

8. In a regulator system, a main-control electromagnet, an auxiliaryelectromagnet, a supply circuit, a resistor, a pair of contact membersgoverned by the main-control magnet for connecting the auxiliary magnetin tive resistor of relatively high value connected across the contactmembers, and a condenser and a resistor connected in parallel to saidauxiliary magnetfor protecting.

the contact members against inductive dis charges. 1

In testimony whereof I have hereunto sllpscribed my name this 31st dayof Oct, 1 8. v p

. CLARENCE A. BODDIE.

